text: /*
   * fs/f2fs/data.c
   *
   * Copyright (c) 2012 Samsung Electronics Co., Ltd.
   *             http://www.samsung.com/
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  #include <linux/fs.h>
  #include <linux/f2fs_fs.h>
  #include <linux/buffer_head.h>
  #include <linux/mpage.h>
  #include <linux/writeback.h>
  #include <linux/backing-dev.h>
  #include <linux/pagevec.h>
  #include <linux/blkdev.h>
  #include <linux/bio.h>
  #include <linux/prefetch.h>
  #include <linux/uio.h>
  #include <linux/cleancache.h>
  
  #include "f2fs.h"
  #include "node.h"
  #include "segment.h"
  #include "trace.h"
  #include <trace/events/f2fs.h>
  
  static void f2fs_read_end_io(struct bio *bio)
  {
  	struct bio_vec *bvec;
  	int i;
  
  	if (f2fs_bio_encrypted(bio)) {
  		if (bio->bi_error) {
  			f2fs_release_crypto_ctx(bio->bi_private);
  		} else {
  			f2fs_end_io_crypto_work(bio->bi_private, bio);
  			return;
  		}
  	}
  
  	bio_for_each_segment_all(bvec, bio, i) {
  		struct page *page = bvec->bv_page;
  
  		if (!bio->bi_error) {
  			SetPageUptodate(page);
  		} else {
  			ClearPageUptodate(page);
  			SetPageError(page);
  		}
  		unlock_page(page);
  	}
  	bio_put(bio);
  }
  
  static void f2fs_write_end_io(struct bio *bio)
  {
  	struct f2fs_sb_info *sbi = bio->bi_private;
  	struct bio_vec *bvec;
  	int i;
  
  	bio_for_each_segment_all(bvec, bio, i) {
  		struct page *page = bvec->bv_page;
  
  		f2fs_restore_and_release_control_page(&page);
  
  		if (unlikely(bio->bi_error)) {
  			set_page_dirty(page);
  			set_bit(AS_EIO, &page->mapping->flags);
  			f2fs_stop_checkpoint(sbi);
  		}
  		end_page_writeback(page);
  		dec_page_count(sbi, F2FS_WRITEBACK);
  	}
  
  	if (!get_pages(sbi, F2FS_WRITEBACK) &&
  			!list_empty(&sbi->cp_wait.task_list))
  		wake_up(&sbi->cp_wait);
  
  	bio_put(bio);
  }
  
  /*
   * Low-level block read/write IO operations.
   */
  static struct bio *__bio_alloc(struct f2fs_sb_info *sbi, block_t blk_addr,
  				int npages, bool is_read)
  {
  	struct bio *bio;
  
  	bio = f2fs_bio_alloc(npages);
  
  	bio->bi_bdev = sbi->sb->s_bdev;
  	bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(blk_addr);
  	bio->bi_end_io = is_read ? f2fs_read_end_io : f2fs_write_end_io;
  	bio->bi_private = is_read ? NULL : sbi;
  
  	return bio;
  }
  
  static void __submit_merged_bio(struct f2fs_bio_info *io)
  {
  	struct f2fs_io_info *fio = &io->fio;
  
  	if (!io->bio)
  		return;
  
  	if (is_read_io(fio->rw))
  		trace_f2fs_submit_read_bio(io->sbi->sb, fio, io->bio);
  	else
  		trace_f2fs_submit_write_bio(io->sbi->sb, fio, io->bio);
  
  	submit_bio(fio->rw, io->bio);
  	io->bio = NULL;
  }
  
  void f2fs_submit_merged_bio(struct f2fs_sb_info *sbi,
  				enum page_type type, int rw)
  {
  	enum page_type btype = PAGE_TYPE_OF_BIO(type);
  	struct f2fs_bio_info *io;
  
  	io = is_read_io(rw) ? &sbi->read_io : &sbi->write_io[btype];
  
  	down_write(&io->io_rwsem);
  
  	/* change META to META_FLUSH in the checkpoint procedure */
  	if (type >= META_FLUSH) {
  		io->fio.type = META_FLUSH;
  		if (test_opt(sbi, NOBARRIER))
  			io->fio.rw = WRITE_FLUSH | REQ_META | REQ_PRIO;
  		else
  			io->fio.rw = WRITE_FLUSH_FUA | REQ_META | REQ_PRIO;
  	}
  	__submit_merged_bio(io);
  	up_write(&io->io_rwsem);
  }
  
  /*
   * Fill the locked page with data located in the block address.
   * Return unlocked page.
   */
  int f2fs_submit_page_bio(struct f2fs_io_info *fio)
  {
  	struct bio *bio;
  	struct page *page = fio->encrypted_page ? fio->encrypted_page : fio->page;
  
  	trace_f2fs_submit_page_bio(page, fio);
  	f2fs_trace_ios(fio, 0);
  
  	/* Allocate a new bio */
  	bio = __bio_alloc(fio->sbi, fio->blk_addr, 1, is_read_io(fio->rw));
  
  	if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
  		bio_put(bio);
  		return -EFAULT;
  	}
  
  	submit_bio(fio->rw, bio);
  	return 0;
  }
  
  void f2fs_submit_page_mbio(struct f2fs_io_info *fio)
  {
  	struct f2fs_sb_info *sbi = fio->sbi;
  	enum page_type btype = PAGE_TYPE_OF_BIO(fio->type);
  	struct f2fs_bio_info *io;
  	bool is_read = is_read_io(fio->rw);
  	struct page *bio_page;
  
  	io = is_read ? &sbi->read_io : &sbi->write_io[btype];
  
  	verify_block_addr(sbi, fio->blk_addr);
  
  	down_write(&io->io_rwsem);
  
  	if (!is_read)
  		inc_page_count(sbi, F2FS_WRITEBACK);
  
  	if (io->bio && (io->last_block_in_bio != fio->blk_addr - 1 ||
  						io->fio.rw != fio->rw))
  		__submit_merged_bio(io);
  alloc_new:
  	if (io->bio == NULL) {
  		int bio_blocks = MAX_BIO_BLOCKS(sbi);
  
  		io->bio = __bio_alloc(sbi, fio->blk_addr, bio_blocks, is_read);
  		io->fio = *fio;
  	}
  
  	bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page;
  
  	if (bio_add_page(io->bio, bio_page, PAGE_CACHE_SIZE, 0) <
  							PAGE_CACHE_SIZE) {
  		__submit_merged_bio(io);
  		goto alloc_new;
  	}
  
  	io->last_block_in_bio = fio->blk_addr;
  	f2fs_trace_ios(fio, 0);
  
  	up_write(&io->io_rwsem);
  	trace_f2fs_submit_page_mbio(fio->page, fio);
  }
  
  /*
   * Lock ordering for the change of data block address:
   * ->data_page
   *  ->node_page
   *    update block addresses in the node page
   */
  void set_data_blkaddr(struct dnode_of_data *dn)
  {
  	struct f2fs_node *rn;
  	__le32 *addr_array;
  	struct page *node_page = dn->node_page;
  	unsigned int ofs_in_node = dn->ofs_in_node;
  
  	f2fs_wait_on_page_writeback(node_page, NODE);
  
  	rn = F2FS_NODE(node_page);
  
  	/* Get physical address of data block */
  	addr_array = blkaddr_in_node(rn);
  	addr_array[ofs_in_node] = cpu_to_le32(dn->data_blkaddr);
  	set_page_dirty(node_page);
  }
  
  int reserve_new_block(struct dnode_of_data *dn)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
  
  	if (unlikely(is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC)))
  		return -EPERM;
  	if (unlikely(!inc_valid_block_count(sbi, dn->inode, 1)))
  		return -ENOSPC;
  
  	trace_f2fs_reserve_new_block(dn->inode, dn->nid, dn->ofs_in_node);
  
  	dn->data_blkaddr = NEW_ADDR;
  	set_data_blkaddr(dn);
  	mark_inode_dirty(dn->inode);
  	sync_inode_page(dn);
  	return 0;
  }
  
  int f2fs_reserve_block(struct dnode_of_data *dn, pgoff_t index)
  {
  	bool need_put = dn->inode_page ? false : true;
  	int err;
  
  	err = get_dnode_of_data(dn, index, ALLOC_NODE);
  	if (err)
  		return err;
  
  	if (dn->data_blkaddr == NULL_ADDR)
  		err = reserve_new_block(dn);
  	if (err || need_put)
  		f2fs_put_dnode(dn);
  	return err;
  }
  
  int f2fs_get_block(struct dnode_of_data *dn, pgoff_t index)
  {
  	struct extent_info ei;
  	struct inode *inode = dn->inode;
  
  	if (f2fs_lookup_extent_cache(inode, index, &ei)) {
  		dn->data_blkaddr = ei.blk + index - ei.fofs;
  		return 0;
  	}
  
  	return f2fs_reserve_block(dn, index);
  }
  
  struct page *get_read_data_page(struct inode *inode, pgoff_t index, int rw)
  {
  	struct address_space *mapping = inode->i_mapping;
  	struct dnode_of_data dn;
  	struct page *page;
  	struct extent_info ei;
  	int err;
  	struct f2fs_io_info fio = {
  		.sbi = F2FS_I_SB(inode),
  		.type = DATA,
  		.rw = rw,
  		.encrypted_page = NULL,
  	};
  
  	if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
  		return read_mapping_page(mapping, index, NULL);
  
  	page = grab_cache_page(mapping, index);
  	if (!page)
  		return ERR_PTR(-ENOMEM);
  
  	if (f2fs_lookup_extent_cache(inode, index, &ei)) {
  		dn.data_blkaddr = ei.blk + index - ei.fofs;
  		goto got_it;
  	}
  
  	set_new_dnode(&dn, inode, NULL, NULL, 0);
  	err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
  	if (err)
  		goto put_err;
  	f2fs_put_dnode(&dn);
  
  	if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
  		err = -ENOENT;
  		goto put_err;
  	}
  got_it:
  	if (PageUptodate(page)) {
  		unlock_page(page);
  		return page;
  	}
  
  	/*
  	 * A new dentry page is allocated but not able to be written, since its
  	 * new inode page couldn't be allocated due to -ENOSPC.
  	 * In such the case, its blkaddr can be remained as NEW_ADDR.
  	 * see, f2fs_add_link -> get_new_data_page -> init_inode_metadata.
  	 */
  	if (dn.data_blkaddr == NEW_ADDR) {
  		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
  		SetPageUptodate(page);
  		unlock_page(page);
  		return page;
  	}
  
  	fio.blk_addr = dn.data_blkaddr;
  	fio.page = page;
  	err = f2fs_submit_page_bio(&fio);
  	if (err)
  		goto put_err;
  	return page;
  
  put_err:
  	f2fs_put_page(page, 1);
  	return ERR_PTR(err);
  }
  
  struct page *find_data_page(struct inode *inode, pgoff_t index)
  {
  	struct address_space *mapping = inode->i_mapping;
  	struct page *page;
  
  	page = find_get_page(mapping, index);
  	if (page && PageUptodate(page))
  		return page;
  	f2fs_put_page(page, 0);
  
  	page = get_read_data_page(inode, index, READ_SYNC);
  	if (IS_ERR(page))
  		return page;
  
  	if (PageUptodate(page))
  		return page;
  
  	wait_on_page_locked(page);
  	if (unlikely(!PageUptodate(page))) {
  		f2fs_put_page(page, 0);
  		return ERR_PTR(-EIO);
  	}
  	return page;
  }
  
  /*
   * If it tries to access a hole, return an error.
   * Because, the callers, functions in dir.c and GC, should be able to know
   * whether this page exists or not.
   */
  struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
  {
  	struct address_space *mapping = inode->i_mapping;
  	struct page *page;
  repeat:
  	page = get_read_data_page(inode, index, READ_SYNC);
  	if (IS_ERR(page))
  		return page;
  
  	/* wait for read completion */
  	lock_page(page);
  	if (unlikely(!PageUptodate(page))) {
  		f2fs_put_page(page, 1);
  		return ERR_PTR(-EIO);
  	}
  	if (unlikely(page->mapping != mapping)) {
  		f2fs_put_page(page, 1);
  		goto repeat;
  	}
  	return page;
  }
  
  /*
   * Caller ensures that this data page is never allocated.
   * A new zero-filled data page is allocated in the page cache.
   *
   * Also, caller should grab and release a rwsem by calling f2fs_lock_op() and
   * f2fs_unlock_op().
   * Note that, ipage is set only by make_empty_dir, and if any error occur,
   * ipage should be released by this function.
   */
  struct page *get_new_data_page(struct inode *inode,
  		struct page *ipage, pgoff_t index, bool new_i_size)
  {
  	struct address_space *mapping = inode->i_mapping;
  	struct page *page;
  	struct dnode_of_data dn;
  	int err;
  repeat:
  	page = grab_cache_page(mapping, index);
  	if (!page) {
  		/*
  		 * before exiting, we should make sure ipage will be released
  		 * if any error occur.
  		 */
  		f2fs_put_page(ipage, 1);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	set_new_dnode(&dn, inode, ipage, NULL, 0);
  	err = f2fs_reserve_block(&dn, index);
  	if (err) {
  		f2fs_put_page(page, 1);
  		return ERR_PTR(err);
  	}
  	if (!ipage)
  		f2fs_put_dnode(&dn);
  
  	if (PageUptodate(page))
  		goto got_it;
  
  	if (dn.data_blkaddr == NEW_ADDR) {
  		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
  		SetPageUptodate(page);
  	} else {
  		f2fs_put_page(page, 1);
  
  		page = get_read_data_page(inode, index, READ_SYNC);
  		if (IS_ERR(page))
  			goto repeat;
  
  		/* wait for read completion */
  		lock_page(page);
  	}
  got_it:
  	if (new_i_size &&
  		i_size_read(inode) < ((index + 1) << PAGE_CACHE_SHIFT)) {
  		i_size_write(inode, ((index + 1) << PAGE_CACHE_SHIFT));
  		/* Only the directory inode sets new_i_size */
  		set_inode_flag(F2FS_I(inode), FI_UPDATE_DIR);
  	}
  	return page;
  }
  
  static int __allocate_data_block(struct dnode_of_data *dn)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
  	struct f2fs_inode_info *fi = F2FS_I(dn->inode);
  	struct f2fs_summary sum;
  	struct node_info ni;
  	int seg = CURSEG_WARM_DATA;
  	pgoff_t fofs;
  
  	if (unlikely(is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC)))
  		return -EPERM;
  
  	dn->data_blkaddr = datablock_addr(dn->node_page, dn->ofs_in_node);
  	if (dn->data_blkaddr == NEW_ADDR)
  		goto alloc;
  
  	if (unlikely(!inc_valid_block_count(sbi, dn->inode, 1)))
  		return -ENOSPC;
  
  alloc:
  	get_node_info(sbi, dn->nid, &ni);
  	set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
  
  	if (dn->ofs_in_node == 0 && dn->inode_page == dn->node_page)
  		seg = CURSEG_DIRECT_IO;
  
  	allocate_data_block(sbi, NULL, dn->data_blkaddr, &dn->data_blkaddr,
  								&sum, seg);
  	set_data_blkaddr(dn);
  
  	/* update i_size */
  	fofs = start_bidx_of_node(ofs_of_node(dn->node_page), fi) +
  							dn->ofs_in_node;
  	if (i_size_read(dn->inode) < ((fofs + 1) << PAGE_CACHE_SHIFT))
  		i_size_write(dn->inode, ((fofs + 1) << PAGE_CACHE_SHIFT));
  
  	/* direct IO doesn't use extent cache to maximize the performance */
  	f2fs_drop_largest_extent(dn->inode, fofs);
  
  	return 0;
  }
  
  static void __allocate_data_blocks(struct inode *inode, loff_t offset,
  							size_t count)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct dnode_of_data dn;
  	u64 start = F2FS_BYTES_TO_BLK(offset);
  	u64 len = F2FS_BYTES_TO_BLK(count);
  	bool allocated;
  	u64 end_offset;
  
  	while (len) {
  		f2fs_balance_fs(sbi);
  		f2fs_lock_op(sbi);
  
  		/* When reading holes, we need its node page */
  		set_new_dnode(&dn, inode, NULL, NULL, 0);
  		if (get_dnode_of_data(&dn, start, ALLOC_NODE))
  			goto out;
  
  		allocated = false;
  		end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
  
  		while (dn.ofs_in_node < end_offset && len) {
  			block_t blkaddr;
  
  			blkaddr = datablock_addr(dn.node_page, dn.ofs_in_node);
  			if (blkaddr == NULL_ADDR || blkaddr == NEW_ADDR) {
  				if (__allocate_data_block(&dn))
  					goto sync_out;
  				allocated = true;
  			}
  			len--;
  			start++;
  			dn.ofs_in_node++;
  		}
  
  		if (allocated)
  			sync_inode_page(&dn);
  
  		f2fs_put_dnode(&dn);
  		f2fs_unlock_op(sbi);
  	}
  	return;
  
  sync_out:
  	if (allocated)
  		sync_inode_page(&dn);
  	f2fs_put_dnode(&dn);
  out:
  	f2fs_unlock_op(sbi);
  	return;
  }
  
  /*
   * f2fs_map_blocks() now supported readahead/bmap/rw direct_IO with
   * f2fs_map_blocks structure.
   * If original data blocks are allocated, then give them to blockdev.
   * Otherwise,
   *     a. preallocate requested block addresses
   *     b. do not use extent cache for better performance
   *     c. give the block addresses to blockdev
   */
  static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
  						int create, int flag)
  {
  	unsigned int maxblocks = map->m_len;
  	struct dnode_of_data dn;
  	int mode = create ? ALLOC_NODE : LOOKUP_NODE_RA;
  	pgoff_t pgofs, end_offset;
  	int err = 0, ofs = 1;
  	struct extent_info ei;
  	bool allocated = false;
  
  	map->m_len = 0;
  	map->m_flags = 0;
  
  	/* it only supports block size == page size */
  	pgofs =	(pgoff_t)map->m_lblk;
  
  	if (f2fs_lookup_extent_cache(inode, pgofs, &ei)) {
  		map->m_pblk = ei.blk + pgofs - ei.fofs;
  		map->m_len = min((pgoff_t)maxblocks, ei.fofs + ei.len - pgofs);
  		map->m_flags = F2FS_MAP_MAPPED;
  		goto out;
  	}
  
  	if (create)
  		f2fs_lock_op(F2FS_I_SB(inode));
  
  	/* When reading holes, we need its node page */
  	set_new_dnode(&dn, inode, NULL, NULL, 0);
  	err = get_dnode_of_data(&dn, pgofs, mode);
  	if (err) {
  		if (err == -ENOENT)
  			err = 0;
  		goto unlock_out;
  	}
  	if (dn.data_blkaddr == NEW_ADDR) {
  		if (flag == F2FS_GET_BLOCK_BMAP) {
  			err = -ENOENT;
  			goto put_out;
  		} else if (flag == F2FS_GET_BLOCK_READ ||
  				flag == F2FS_GET_BLOCK_DIO) {
  			goto put_out;
  		}
  		/*
  		 * if it is in fiemap call path (flag = F2FS_GET_BLOCK_FIEMAP),
  		 * mark it as mapped and unwritten block.
  		 */
  	}
  
  	if (dn.data_blkaddr != NULL_ADDR) {
  		map->m_flags = F2FS_MAP_MAPPED;
  		map->m_pblk = dn.data_blkaddr;
  		if (dn.data_blkaddr == NEW_ADDR)
  			map->m_flags |= F2FS_MAP_UNWRITTEN;
  	} else if (create) {
  		err = __allocate_data_block(&dn);
  		if (err)
  			goto put_out;
  		allocated = true;
  		map->m_flags = F2FS_MAP_NEW | F2FS_MAP_MAPPED;
  		map->m_pblk = dn.data_blkaddr;
  	} else {
  		if (flag == F2FS_GET_BLOCK_BMAP)
  			err = -ENOENT;
  		goto put_out;
  	}
  
  	end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
  	map->m_len = 1;
  	dn.ofs_in_node++;
  	pgofs++;
  
  get_next:
  	if (dn.ofs_in_node >= end_offset) {
  		if (allocated)
  			sync_inode_page(&dn);
  		allocated = false;
  		f2fs_put_dnode(&dn);
  
  		set_new_dnode(&dn, inode, NULL, NULL, 0);
  		err = get_dnode_of_data(&dn, pgofs, mode);
  		if (err) {
  			if (err == -ENOENT)
  				err = 0;
  			goto unlock_out;
  		}
  
  		if (dn.data_blkaddr == NEW_ADDR &&
  				flag != F2FS_GET_BLOCK_FIEMAP)
  			goto put_out;
  
  		end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
  	}
  
  	if (maxblocks > map->m_len) {
  		block_t blkaddr = datablock_addr(dn.node_page, dn.ofs_in_node);
  		if (blkaddr == NULL_ADDR && create) {
  			err = __allocate_data_block(&dn);
  			if (err)
  				goto sync_out;
  			allocated = true;
  			map->m_flags |= F2FS_MAP_NEW;
  			blkaddr = dn.data_blkaddr;
  		}
  		/* Give more consecutive addresses for the readahead */
  		if ((map->m_pblk != NEW_ADDR &&
  				blkaddr == (map->m_pblk + ofs)) ||
  				(map->m_pblk == NEW_ADDR &&
  				blkaddr == NEW_ADDR)) {
  			ofs++;
  			dn.ofs_in_node++;
  			pgofs++;
  			map->m_len++;
  			goto get_next;
  		}
  	}
  sync_out:
  	if (allocated)
  		sync_inode_page(&dn);
  put_out:
  	f2fs_put_dnode(&dn);
  unlock_out:
  	if (create)
  		f2fs_unlock_op(F2FS_I_SB(inode));
  out:
  	trace_f2fs_map_blocks(inode, map, err);
  	return err;
  }
  
  static int __get_data_block(struct inode *inode, sector_t iblock,
  			struct buffer_head *bh, int create, int flag)
  {
  	struct f2fs_map_blocks map;
  	int ret;
  
  	map.m_lblk = iblock;
  	map.m_len = bh->b_size >> inode->i_blkbits;
  
  	ret = f2fs_map_blocks(inode, &map, create, flag);
  	if (!ret) {
  		map_bh(bh, inode->i_sb, map.m_pblk);
  		bh->b_state = (bh->b_state & ~F2FS_MAP_FLAGS) | map.m_flags;
  		bh->b_size = map.m_len << inode->i_blkbits;
  	}
  	return ret;
  }
  
  static int get_data_block(struct inode *inode, sector_t iblock,
  			struct buffer_head *bh_result, int create, int flag)
  {
  	return __get_data_block(inode, iblock, bh_result, create, flag);
  }
  
  static int get_data_block_dio(struct inode *inode, sector_t iblock,
  			struct buffer_head *bh_result, int create)
  {
  	return __get_data_block(inode, iblock, bh_result, create,
  						F2FS_GET_BLOCK_DIO);
  }
  
  static int get_data_block_bmap(struct inode *inode, sector_t iblock,
  			struct buffer_head *bh_result, int create)
  {
  	return __get_data_block(inode, iblock, bh_result, create,
  						F2FS_GET_BLOCK_BMAP);
  }
  
  static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
  {
  	return (offset >> inode->i_blkbits);
  }
  
  static inline loff_t blk_to_logical(struct inode *inode, sector_t blk)
  {
  	return (blk << inode->i_blkbits);
  }
  
  int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
  		u64 start, u64 len)
  {
  	struct buffer_head map_bh;
  	sector_t start_blk, last_blk;
  	loff_t isize = i_size_read(inode);
  	u64 logical = 0, phys = 0, size = 0;
  	u32 flags = 0;
  	bool past_eof = false, whole_file = false;
  	int ret = 0;
  
  	ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
  	if (ret)
  		return ret;
  
  	mutex_lock(&inode->i_mutex);
  
  	if (len >= isize) {
  		whole_file = true;
  		len = isize;
  	}
  
  	if (logical_to_blk(inode, len) == 0)
  		len = blk_to_logical(inode, 1);
  
  	start_blk = logical_to_blk(inode, start);
  	last_blk = logical_to_blk(inode, start + len - 1);
  next:
  	memset(&map_bh, 0, sizeof(struct buffer_head));
  	map_bh.b_size = len;
  
  	ret = get_data_block(inode, start_blk, &map_bh, 0,
  					F2FS_GET_BLOCK_FIEMAP);
  	if (ret)
  		goto out;
  
  	/* HOLE */
  	if (!buffer_mapped(&map_bh)) {
  		start_blk++;
  
  		if (!past_eof && blk_to_logical(inode, start_blk) >= isize)
  			past_eof = 1;
  
  		if (past_eof && size) {
  			flags |= FIEMAP_EXTENT_LAST;
  			ret = fiemap_fill_next_extent(fieinfo, logical,
  					phys, size, flags);
  		} else if (size) {
  			ret = fiemap_fill_next_extent(fieinfo, logical,
  					phys, size, flags);
  			size = 0;
  		}
  
  		/* if we have holes up to/past EOF then we're done */
  		if (start_blk > last_blk || past_eof || ret)
  			goto out;
  	} else {
  		if (start_blk > last_blk && !whole_file) {
  			ret = fiemap_fill_next_extent(fieinfo, logical,
  					phys, size, flags);
  			goto out;
  		}
  
  		/*
  		 * if size != 0 then we know we already have an extent
  		 * to add, so add it.
  		 */
  		if (size) {
  			ret = fiemap_fill_next_extent(fieinfo, logical,
  					phys, size, flags);
  			if (ret)
  				goto out;
  		}
  
  		logical = blk_to_logical(inode, start_blk);
  		phys = blk_to_logical(inode, map_bh.b_blocknr);
  		size = map_bh.b_size;
  		flags = 0;
  		if (buffer_unwritten(&map_bh))
  			flags = FIEMAP_EXTENT_UNWRITTEN;
  
  		start_blk += logical_to_blk(inode, size);
  
  		/*
  		 * If we are past the EOF, then we need to make sure as
  		 * soon as we find a hole that the last extent we found
  		 * is marked with FIEMAP_EXTENT_LAST
  		 */
  		if (!past_eof && logical + size >= isize)
  			past_eof = true;
  	}
  	cond_resched();
  	if (fatal_signal_pending(current))
  		ret = -EINTR;
  	else
  		goto next;
  out:
  	if (ret == 1)
  		ret = 0;
  
  	mutex_unlock(&inode->i_mutex);
  	return ret;
  }
  
  /*
   * This function was originally taken from fs/mpage.c, and customized for f2fs.
   * Major change was from block_size == page_size in f2fs by default.
   */
  static int f2fs_mpage_readpages(struct address_space *mapping,
  			struct list_head *pages, struct page *page,
  			unsigned nr_pages)
  {
  	struct bio *bio = NULL;
  	unsigned page_idx;
  	sector_t last_block_in_bio = 0;
  	struct inode *inode = mapping->host;
  	const unsigned blkbits = inode->i_blkbits;
  	const unsigned blocksize = 1 << blkbits;
  	sector_t block_in_file;
  	sector_t last_block;
  	sector_t last_block_in_file;
  	sector_t block_nr;
  	struct block_device *bdev = inode->i_sb->s_bdev;
  	struct f2fs_map_blocks map;
  
  	map.m_pblk = 0;
  	map.m_lblk = 0;
  	map.m_len = 0;
  	map.m_flags = 0;
  
  	for (page_idx = 0; nr_pages; page_idx++, nr_pages--) {
  
  		prefetchw(&page->flags);
  		if (pages) {
  			page = list_entry(pages->prev, struct page, lru);
  			list_del(&page->lru);
  			if (add_to_page_cache_lru(page, mapping,
  						  page->index, GFP_KERNEL))
  				goto next_page;
  		}
  
  		block_in_file = (sector_t)page->index;
  		last_block = block_in_file + nr_pages;
  		last_block_in_file = (i_size_read(inode) + blocksize - 1) >>
  								blkbits;
  		if (last_block > last_block_in_file)
  			last_block = last_block_in_file;
  
  		/*
  		 * Map blocks using the previous result first.
  		 */
  		if ((map.m_flags & F2FS_MAP_MAPPED) &&
  				block_in_file > map.m_lblk &&
  				block_in_file < (map.m_lblk + map.m_len))
  			goto got_it;
  
  		/*
  		 * Then do more f2fs_map_blocks() calls until we are
  		 * done with this page.
  		 */
  		map.m_flags = 0;
  
  		if (block_in_file < last_block) {
  			map.m_lblk = block_in_file;
  			map.m_len = last_block - block_in_file;
  
  			if (f2fs_map_blocks(inode, &map, 0, false))
  				goto set_error_page;
  		}
  got_it:
  		if ((map.m_flags & F2FS_MAP_MAPPED)) {
  			block_nr = map.m_pblk + block_in_file - map.m_lblk;
  			SetPageMappedToDisk(page);
  
  			if (!PageUptodate(page) && !cleancache_get_page(page)) {
  				SetPageUptodate(page);
  				goto confused;
  			}
  		} else {
  			zero_user_segment(page, 0, PAGE_CACHE_SIZE);
  			SetPageUptodate(page);
  			unlock_page(page);
  			goto next_page;
  		}
  
  		/*
  		 * This page will go to BIO.  Do we need to send this
  		 * BIO off first?
  		 */
  		if (bio && (last_block_in_bio != block_nr - 1)) {
  submit_and_realloc:
  			submit_bio(READ, bio);
  			bio = NULL;
  		}
  		if (bio == NULL) {
  			struct f2fs_crypto_ctx *ctx = NULL;
  
  			if (f2fs_encrypted_inode(inode) &&
  					S_ISREG(inode->i_mode)) {
  				struct page *cpage;
  
  				ctx = f2fs_get_crypto_ctx(inode);
  				if (IS_ERR(ctx))
  					goto set_error_page;
  
  				/* wait the page to be moved by cleaning */
  				cpage = find_lock_page(
  						META_MAPPING(F2FS_I_SB(inode)),
  						block_nr);
  				if (cpage) {
  					f2fs_wait_on_page_writeback(cpage,
  									DATA);
  					f2fs_put_page(cpage, 1);
  				}
  			}
  
  			bio = bio_alloc(GFP_KERNEL,
  				min_t(int, nr_pages, BIO_MAX_PAGES));
  			if (!bio) {
  				if (ctx)
  					f2fs_release_crypto_ctx(ctx);
  				goto set_error_page;
  			}
  			bio->bi_bdev = bdev;
  			bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(block_nr);
  			bio->bi_end_io = f2fs_read_end_io;
  			bio->bi_private = ctx;
  		}
  
  		if (bio_add_page(bio, page, blocksize, 0) < blocksize)
  			goto submit_and_realloc;
  
  		last_block_in_bio = block_nr;
  		goto next_page;
  set_error_page:
  		SetPageError(page);
  		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
  		unlock_page(page);
  		goto next_page;
  confused:
  		if (bio) {
  			submit_bio(READ, bio);
  			bio = NULL;
  		}
  		unlock_page(page);
  next_page:
  		if (pages)
  			page_cache_release(page);
  	}
  	BUG_ON(pages && !list_empty(pages));
  	if (bio)
  		submit_bio(READ, bio);
  	return 0;
  }
  
  static int f2fs_read_data_page(struct file *file, struct page *page)
  {
  	struct inode *inode = page->mapping->host;
  	int ret = -EAGAIN;
  
  	trace_f2fs_readpage(page, DATA);
  
  	/* If the file has inline data, try to read it directly */
  	if (f2fs_has_inline_data(inode))
  		ret = f2fs_read_inline_data(inode, page);
  	if (ret == -EAGAIN)
  		ret = f2fs_mpage_readpages(page->mapping, NULL, page, 1);
  	return ret;
  }
  
  static int f2fs_read_data_pages(struct file *file,
  			struct address_space *mapping,
  			struct list_head *pages, unsigned nr_pages)
  {
  	struct inode *inode = file->f_mapping->host;
  
  	/* If the file has inline data, skip readpages */
  	if (f2fs_has_inline_data(inode))
  		return 0;
  
  	return f2fs_mpage_readpages(mapping, pages, NULL, nr_pages);
  }
  
  int do_write_data_page(struct f2fs_io_info *fio)
  {
  	struct page *page = fio->page;
  	struct inode *inode = page->mapping->host;
  	struct dnode_of_data dn;
  	int err = 0;
  
  	set_new_dnode(&dn, inode, NULL, NULL, 0);
  	err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
  	if (err)
  		return err;
  
  	fio->blk_addr = dn.data_blkaddr;
  
  	/* This page is already truncated */
  	if (fio->blk_addr == NULL_ADDR) {
  		ClearPageUptodate(page);
  		goto out_writepage;
  	}
  
  	if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
  		fio->encrypted_page = f2fs_encrypt(inode, fio->page);
  		if (IS_ERR(fio->encrypted_page)) {
  			err = PTR_ERR(fio->encrypted_page);
  			goto out_writepage;
  		}
  	}
  
  	set_page_writeback(page);
  
  	/*
  	 * If current allocation needs SSR,
  	 * it had better in-place writes for updated data.
  	 */
  	if (unlikely(fio->blk_addr != NEW_ADDR &&
  			!is_cold_data(page) &&
  			need_inplace_update(inode))) {
  		rewrite_data_page(fio);
  		set_inode_flag(F2FS_I(inode), FI_UPDATE_WRITE);
  		trace_f2fs_do_write_data_page(page, IPU);
  	} else {
  		write_data_page(&dn, fio);
  		set_data_blkaddr(&dn);
  		f2fs_update_extent_cache(&dn);
  		trace_f2fs_do_write_data_page(page, OPU);
  		set_inode_flag(F2FS_I(inode), FI_APPEND_WRITE);
  		if (page->index == 0)
  			set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);
  	}
  out_writepage:
  	f2fs_put_dnode(&dn);
  	return err;
  }
  
  static int f2fs_write_data_page(struct page *page,
  					struct writeback_control *wbc)
  {
  	struct inode *inode = page->mapping->host;
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	loff_t i_size = i_size_read(inode);
  	const pgoff_t end_index = ((unsigned long long) i_size)
  							>> PAGE_CACHE_SHIFT;
  	unsigned offset = 0;
  	bool need_balance_fs = false;
  	int err = 0;
  	struct f2fs_io_info fio = {
  		.sbi = sbi,
  		.type = DATA,
  		.rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE,
  		.page = page,
  		.encrypted_page = NULL,
  	};
  
  	trace_f2fs_writepage(page, DATA);
  
  	if (page->index < end_index)
  		goto write;
  
  	/*
  	 * If the offset is out-of-range of file size,
  	 * this page does not have to be written to disk.
  	 */
  	offset = i_size & (PAGE_CACHE_SIZE - 1);
  	if ((page->index >= end_index + 1) || !offset)
  		goto out;
  
  	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
  write:
  	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
  		goto redirty_out;
  	if (f2fs_is_drop_cache(inode))
  		goto out;
  	if (f2fs_is_volatile_file(inode) && !wbc->for_reclaim &&
  			available_free_memory(sbi, BASE_CHECK))
  		goto redirty_out;
  
  	/* Dentry blocks are controlled by checkpoint */
  	if (S_ISDIR(inode->i_mode)) {
  		if (unlikely(f2fs_cp_error(sbi)))
  			goto redirty_out;
  		err = do_write_data_page(&fio);
  		goto done;
  	}
  
  	/* we should bypass data pages to proceed the kworkder jobs */
  	if (unlikely(f2fs_cp_error(sbi))) {
  		SetPageError(page);
  		goto out;
  	}
  
  	if (!wbc->for_reclaim)
  		need_balance_fs = true;
  	else if (has_not_enough_free_secs(sbi, 0))
  		goto redirty_out;
  
  	err = -EAGAIN;
  	f2fs_lock_op(sbi);
  	if (f2fs_has_inline_data(inode))
  		err = f2fs_write_inline_data(inode, page);
  	if (err == -EAGAIN)
  		err = do_write_data_page(&fio);
  	f2fs_unlock_op(sbi);
  done:
  	if (err && err != -ENOENT)
  		goto redirty_out;
  
  	clear_cold_data(page);
  out:
  	inode_dec_dirty_pages(inode);
  	if (err)
  		ClearPageUptodate(page);
  	unlock_page(page);
  	if (need_balance_fs)
  		f2fs_balance_fs(sbi);
  	if (wbc->for_reclaim)
  		f2fs_submit_merged_bio(sbi, DATA, WRITE);
  	return 0;
  
  redirty_out:
  	redirty_page_for_writepage(wbc, page);
  	return AOP_WRITEPAGE_ACTIVATE;
  }
  
  static int __f2fs_writepage(struct page *page, struct writeback_control *wbc,
  			void *data)
  {
  	struct address_space *mapping = data;
  	int ret = mapping->a_ops->writepage(page, wbc);
  	mapping_set_error(mapping, ret);
  	return ret;
  }
  
  /*
   * This function was copied from write_cche_pages from mm/page-writeback.c.
   * The major change is making write step of cold data page separately from
   * warm/hot data page.
   */
  static int f2fs_write_cache_pages(struct address_space *mapping,
  			struct writeback_control *wbc, writepage_t writepage,
  			void *data)
  {
  	int ret = 0;
  	int done = 0;
  	struct pagevec pvec;
  	int nr_pages;
  	pgoff_t uninitialized_var(writeback_index);
  	pgoff_t index;
  	pgoff_t end;		/* Inclusive */
  	pgoff_t done_index;
  	int cycled;
  	int range_whole = 0;
  	int tag;
  	int step = 0;
  
  	pagevec_init(&pvec, 0);
  next:
  	if (wbc->range_cyclic) {
  		writeback_index = mapping->writeback_index; /* prev offset */
  		index = writeback_index;
  		if (index == 0)
  			cycled = 1;
  		else
  			cycled = 0;
  		end = -1;
  	} else {
  		index = wbc->range_start >> PAGE_CACHE_SHIFT;
  		end = wbc->range_end >> PAGE_CACHE_SHIFT;
  		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
  			range_whole = 1;
  		cycled = 1; /* ignore range_cyclic tests */
  	}
  	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
  		tag = PAGECACHE_TAG_TOWRITE;
  	else
  		tag = PAGECACHE_TAG_DIRTY;
  retry:
  	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
  		tag_pages_for_writeback(mapping, index, end);
  	done_index = index;
  	while (!done && (index <= end)) {
  		int i;
  
  		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
  			      min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1);
  		if (nr_pages == 0)
  			break;
  
  		for (i = 0; i < nr_pages; i++) {
  			struct page *page = pvec.pages[i];
  
  			if (page->index > end) {
  				done = 1;
  				break;
  			}
  
  			done_index = page->index;
  
  			lock_page(page);
  
  			if (unlikely(page->mapping != mapping)) {
  continue_unlock:
  				unlock_page(page);
  				continue;
  			}
  
  			if (!PageDirty(page)) {
  				/* someone wrote it for us */
  				goto continue_unlock;
  			}
  
  			if (step == is_cold_data(page))
  				goto continue_unlock;
  
  			if (PageWriteback(page)) {
  				if (wbc->sync_mode != WB_SYNC_NONE)
  					f2fs_wait_on_page_writeback(page, DATA);
  				else
  					goto continue_unlock;
  			}
  
  			BUG_ON(PageWriteback(page));
  			if (!clear_page_dirty_for_io(page))
  				goto continue_unlock;
  
  			ret = (*writepage)(page, wbc, data);
  			if (unlikely(ret)) {
  				if (ret == AOP_WRITEPAGE_ACTIVATE) {
  					unlock_page(page);
  					ret = 0;
  				} else {
  					done_index = page->index + 1;
  					done = 1;
  					break;
  				}
  			}
  
  			if (--wbc->nr_to_write <= 0 &&
  			    wbc->sync_mode == WB_SYNC_NONE) {
  				done = 1;
  				break;
  			}
  		}
  		pagevec_release(&pvec);
  		cond_resched();
  	}
  
  	if (step < 1) {
  		step++;
  		goto next;
  	}
  
  	if (!cycled && !done) {
  		cycled = 1;
  		index = 0;
  		end = writeback_index - 1;
  		goto retry;
  	}
  	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
  		mapping->writeback_index = done_index;
  
  	return ret;
  }
  
  static int f2fs_write_data_pages(struct address_space *mapping,
  			    struct writeback_control *wbc)
  {
  	struct inode *inode = mapping->host;
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	bool locked = false;
  	int ret;
  	long diff;
  
  	trace_f2fs_writepages(mapping->host, wbc, DATA);
  
  	/* deal with chardevs and other special file */
  	if (!mapping->a_ops->writepage)
  		return 0;
  
  	/* skip writing if there is no dirty page in this inode */
  	if (!get_dirty_pages(inode) && wbc->sync_mode == WB_SYNC_NONE)
  		return 0;
  
  	if (S_ISDIR(inode->i_mode) && wbc->sync_mode == WB_SYNC_NONE &&
  			get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) &&
  			available_free_memory(sbi, DIRTY_DENTS))
  		goto skip_write;
  
  	/* during POR, we don't need to trigger writepage at all. */
  	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
  		goto skip_write;
  
  	diff = nr_pages_to_write(sbi, DATA, wbc);
  
  	if (!S_ISDIR(inode->i_mode)) {
  		mutex_lock(&sbi->writepages);
  		locked = true;
  	}
  	ret = f2fs_write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
  	f2fs_submit_merged_bio(sbi, DATA, WRITE);
  	if (locked)
  		mutex_unlock(&sbi->writepages);
  
  	remove_dirty_dir_inode(inode);
  
  	wbc->nr_to_write = max((long)0, wbc->nr_to_write - diff);
  	return ret;
  
  skip_write:
  	wbc->pages_skipped += get_dirty_pages(inode);
  	return 0;
  }
  
  static void f2fs_write_failed(struct address_space *mapping, loff_t to)
  {
  	struct inode *inode = mapping->host;
  
  	if (to > inode->i_size) {
  		truncate_pagecache(inode, inode->i_size);
  		truncate_blocks(inode, inode->i_size, true);
  	}
  }
  
  static int f2fs_write_begin(struct file *file, struct address_space *mapping,
  		loff_t pos, unsigned len, unsigned flags,
  		struct page **pagep, void **fsdata)
  {
  	struct inode *inode = mapping->host;
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct page *page = NULL;
  	struct page *ipage;
  	pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
  	struct dnode_of_data dn;
  	int err = 0;
  
  	trace_f2fs_write_begin(inode, pos, len, flags);
  
  	f2fs_balance_fs(sbi);
  
  	/*
  	 * We should check this at this moment to avoid deadlock on inode page
  	 * and #0 page. The locking rule for inline_data conversion should be:
  	 * lock_page(page #0) -> lock_page(inode_page)
  	 */
  	if (index != 0) {
  		err = f2fs_convert_inline_inode(inode);
  		if (err)
  			goto fail;
  	}
  repeat:
  	page = grab_cache_page_write_begin(mapping, index, flags);
  	if (!page) {
  		err = -ENOMEM;
  		goto fail;
  	}
  
  	*pagep = page;
  
  	f2fs_lock_op(sbi);
  
  	/* check inline_data */
  	ipage = get_node_page(sbi, inode->i_ino);
  	if (IS_ERR(ipage)) {
  		err = PTR_ERR(ipage);
  		goto unlock_fail;
  	}
  
  	set_new_dnode(&dn, inode, ipage, ipage, 0);
  
  	if (f2fs_has_inline_data(inode)) {
  		if (pos + len <= MAX_INLINE_DATA) {
  			read_inline_data(page, ipage);
  			set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
  			sync_inode_page(&dn);
  			goto put_next;
  		}
  		err = f2fs_convert_inline_page(&dn, page);
  		if (err)
  			goto put_fail;
  	}
  
  	err = f2fs_get_block(&dn, index);
  	if (err)
  		goto put_fail;
  put_next:
  	f2fs_put_dnode(&dn);
  	f2fs_unlock_op(sbi);
  
  	f2fs_wait_on_page_writeback(page, DATA);
  
  	if (len == PAGE_CACHE_SIZE)
  		goto out_update;
  	if (PageUptodate(page))
  		goto out_clear;
  
  	if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
  		unsigned start = pos & (PAGE_CACHE_SIZE - 1);
  		unsigned end = start + len;
  
  		/* Reading beyond i_size is simple: memset to zero */
  		zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
  		goto out_update;
  	}
  
  	if (dn.data_blkaddr == NEW_ADDR) {
  		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
  	} else {
  		struct f2fs_io_info fio = {
  			.sbi = sbi,
  			.type = DATA,
  			.rw = READ_SYNC,
  			.blk_addr = dn.data_blkaddr,
  			.page = page,
  			.encrypted_page = NULL,
  		};
  		err = f2fs_submit_page_bio(&fio);
  		if (err)
  			goto fail;
  
  		lock_page(page);
  		if (unlikely(!PageUptodate(page))) {
  			err = -EIO;
  			goto fail;
  		}
  		if (unlikely(page->mapping != mapping)) {
  			f2fs_put_page(page, 1);
  			goto repeat;
  		}
  
  		/* avoid symlink page */
  		if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
  			err = f2fs_decrypt_one(inode, page);
  			if (err)
  				goto fail;
  		}
  	}
  out_update:
  	SetPageUptodate(page);
  out_clear:
  	clear_cold_data(page);
  	return 0;
  
  put_fail:
  	f2fs_put_dnode(&dn);
  unlock_fail:
  	f2fs_unlock_op(sbi);
  fail:
  	f2fs_put_page(page, 1);
  	f2fs_write_failed(mapping, pos + len);
  	return err;
  }
  
  static int f2fs_write_end(struct file *file,
  			struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *page, void *fsdata)
  {
  	struct inode *inode = page->mapping->host;
  
  	trace_f2fs_write_end(inode, pos, len, copied);
  
  	set_page_dirty(page);
  
  	if (pos + copied > i_size_read(inode)) {
  		i_size_write(inode, pos + copied);
  		mark_inode_dirty(inode);
  		update_inode_page(inode);
  	}
  
  	f2fs_put_page(page, 1);
  	return copied;
  }
  
  static int check_direct_IO(struct inode *inode, struct iov_iter *iter,
  			   loff_t offset)
  {
  	unsigned blocksize_mask = inode->i_sb->s_blocksize - 1;
  
  	if (offset & blocksize_mask)
  		return -EINVAL;
  
  	if (iov_iter_alignment(iter) & blocksize_mask)
  		return -EINVAL;
  
  	return 0;
  }
  
  static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
  			      loff_t offset)
  {
  	struct file *file = iocb->ki_filp;
  	struct address_space *mapping = file->f_mapping;
  	struct inode *inode = mapping->host;
  	size_t count = iov_iter_count(iter);
  	int err;
  
  	/* we don't need to use inline_data strictly */
  	if (f2fs_has_inline_data(inode)) {
  		err = f2fs_convert_inline_inode(inode);
  		if (err)
  			return err;
  	}
  
  	if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
  		return 0;
  
  	err = check_direct_IO(inode, iter, offset);
  	if (err)
  		return err;
  
  	trace_f2fs_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
  
  	if (iov_iter_rw(iter) == WRITE)
  		__allocate_data_blocks(inode, offset, count);
  
  	err = blockdev_direct_IO(iocb, inode, iter, offset, get_data_block_dio);
  	if (err < 0 && iov_iter_rw(iter) == WRITE)
  		f2fs_write_failed(mapping, offset + count);
  
  	trace_f2fs_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), err);
  
  	return err;
  }
  
  void f2fs_invalidate_page(struct page *page, unsigned int offset,
  							unsigned int length)
  {
  	struct inode *inode = page->mapping->host;
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  
  	if (inode->i_ino >= F2FS_ROOT_INO(sbi) &&
  		(offset % PAGE_CACHE_SIZE || length != PAGE_CACHE_SIZE))
  		return;
  
  	if (PageDirty(page)) {
  		if (inode->i_ino == F2FS_META_INO(sbi))
  			dec_page_count(sbi, F2FS_DIRTY_META);
  		else if (inode->i_ino == F2FS_NODE_INO(sbi))
  			dec_page_count(sbi, F2FS_DIRTY_NODES);
  		else
  			inode_dec_dirty_pages(inode);
  	}
  
  	/* This is atomic written page, keep Private */
  	if (IS_ATOMIC_WRITTEN_PAGE(page))
  		return;
  
  	ClearPagePrivate(page);
  }
  
  int f2fs_release_page(struct page *page, gfp_t wait)
  {
  	/* If this is dirty page, keep PagePrivate */
  	if (PageDirty(page))
  		return 0;
  
  	/* This is atomic written page, keep Private */
  	if (IS_ATOMIC_WRITTEN_PAGE(page))
  		return 0;
  
  	ClearPagePrivate(page);
  	return 1;
  }
  
  static int f2fs_set_data_page_dirty(struct page *page)
  {
  	struct address_space *mapping = page->mapping;
  	struct inode *inode = mapping->host;
  
  	trace_f2fs_set_page_dirty(page, DATA);
  
  	SetPageUptodate(page);
  
  	if (f2fs_is_atomic_file(inode)) {
  		if (!IS_ATOMIC_WRITTEN_PAGE(page)) {
  			register_inmem_page(inode, page);
  			return 1;
  		}
  		/*
  		 * Previously, this page has been registered, we just
  		 * return here.
  		 */
  		return 0;
  	}
  
  	if (!PageDirty(page)) {
  		__set_page_dirty_nobuffers(page);
  		update_dirty_page(inode, page);
  		return 1;
  	}
  	return 0;
  }
  
  static sector_t f2fs_bmap(struct address_space *mapping, sector_t block)
  {
  	struct inode *inode = mapping->host;
  
  	/* we don't need to use inline_data strictly */
  	if (f2fs_has_inline_data(inode)) {
  		int err = f2fs_convert_inline_inode(inode);
  		if (err)
  			return err;
  	}
  	return generic_block_bmap(mapping, block, get_data_block_bmap);
  }
  
  const struct address_space_operations f2fs_dblock_aops = {
  	.readpage	= f2fs_read_data_page,
  	.readpages	= f2fs_read_data_pages,
  	.writepage	= f2fs_write_data_page,
  	.writepages	= f2fs_write_data_pages,
  	.write_begin	= f2fs_write_begin,
  	.write_end	= f2fs_write_end,
  	.set_page_dirty	= f2fs_set_data_page_dirty,
  	.invalidatepage	= f2fs_invalidate_page,
  	.releasepage	= f2fs_release_page,
  	.direct_IO	= f2fs_direct_IO,
  	.bmap		= f2fs_bmap,
  };
  